MARKING SCHEME
451/1
COMPUTER STUDIES
Paper 1
THEORY
DECEMBER 2021
2 ½ Hours
BUNAMFAN JOINT MOCK EXAMINATION
Kenya Certificate of Secondary Education (K.C.S.E)
INSTRUCTIONS TO CANDIDATES:
·
·
Answer ALL the questions in section A
Answer question 16 (compulsory) and any other three questions from section B.
For Official Use Only
Question
Maximum score
Actual score
1-16
17
18
19
20
TOTAL SCORE
This paper consists of 14 printed pages
Candidates should check the question paper to ensure that all the printed pages are printed as indicated and no
questions are missing.
1
SECTION A:(40 MARKS)
ANSWER ALL QUESTIONS IN THE SPACES PROVIDED
1. i) Explain the emerging trends in microcomputer technology in relation to Size
(1mk)
-PCs are becoming small and portable, e.g. personal Digital Assistant (PDA). (correct @1mk)
ii) Mention two Analogue devices
(2mks)
-Computer used to control a flight Simulator for training pilots
-Bathroom scale
-Thermometer
-Speedometer
-Post- office scale
-A radio with a knob that slides in a slot to increase volume
2. i Identify and briefly describe three advantages of using computers in banking
(1½mks)
-Speed and accuracy
-Easy to access information
-Easy to update records
-Requires less space for storage
-Improves data security and privacy
(first 2@2mks)
ii) State two advantages of using a mouse instead of a keyboard.
(1mk)
- The mouse is easy & convenient to use.
- Modern software includes an option to use it.
- It selects a position on screen much more quickly than a keyboard.
(first two correctr @ 1mk, ½ mk each)
3. State two reasons why Magnetic tapes are not commonly used as computer data storage medium
today (1mk)
-Are slow when retrieving data. This is because of the linear storage of data on the tape.
-Do not fully use their recording surface due to inter- record Gaps
(first 2 correct @ 1mk, ½ mk each)
2
4. i) Give two advantages of the higher number of pixels per square centimeter
(1mk)
- Higher screen resolution
-Displays of sharp & clear images
-The screen is able to display a higher number of different images (first 2 correct @ 1mk, ½ mk
each)
ii) Differentiate between Data interface cable and power cable
(1mk)
Data interface cable -These are special cables that connect all the peripheral devices to the
motherboard and the CPU. They transmit data signals and information to and from the devices
Power cable - Cable that supplies power to devices
(correct @ 1mk)
iii) Explain two differences between serial and parallel communication ports of a computer
(2mks)
-Serial ports have 9 pins, while parallel ports have holes for 9 or 25 pins
-Parallel cables transmit several bits of data simultaneously, while serial cables transmit One
bit at a time
-Serial cables are slower than parallel cable
-Serial cables allow for 2 ways communication (i.e. communication to and from the computer
and the device connected to it) while parallel cables usually offer 1- way communication.
(first 2 @ 2mks)
5. i) What is line spacing as used in word processing?
-The vertical distance between two text lines in a document
ii) Describe any two line spacing specification used in Microsoft Word.
(½mk)
(correct @ ½ mk)
(1mk)
i)Single space – accommodates the largest font in a line
ii)1.5 line space- 1 ½ time that of single line spacing
iii)Double – twice that of single line spacing
iv)Exactly – a fixed line spacing that word does not adjust
v)At least – the minimum line spacing that is needed to fit the largest font or graphic on the
line.
vi)Multiple- a line spacing that is increased or decreased by a percentage that you specify
(first 2 @ 2mks, each ½ mk)
3
iii) Name the two documents used in mail merge
(1mk)
- main document
- Data source
(correct @ 1mk)
iv). With reference to the concept of graphics as used in Microsoft word. Explain the difference between
object linking and embedding?
(1mk)
-In linking, the object imported can only be edited in the original application from which it was
created.
-In embedding, the object imported becomes part of the current application and can be edited
there.
(correct @ 1mk)
6. Who am I?
(3mks)
i) Am is skilled in software/program development as per requirement and technical operations of
computer hardware. I also develop and update both system and application software together with the
associated documentations.
-A Software developer/Engineer
(correct @ 1mk)
ii) Am is skilled in designing computer hardware and also improves on existing ones.
-A Computer engineer
(correct @ 1mk)
iii) I maintain, update & modify information on the websites to meet new demands by the users. I also
monitor the access & use of internet connection by enforcing security measures
-A Web or Network Administrator (correct @ 1mk)
7. During the COVID 19 pandemic, the government advised the citizens to use electronic funds transfer
and other popular mobile phone money transactions to make payments.
i) State how the above method of conducting business would help to curb on the spread of the disease
(2mks)
-Instant – One receive s the money –During the lockdowns people were able to send financial
support easily
-Used as a measure to quarantine or curb spread of COVID 19 which spreads easily through
hands and infected items or surfaces
-Digital payments allow people to access goods and services while in quarantine or social
distancing.
-digital payments were such an alternative to boosting or sustaining e-commerce in the country.
4
- Local Governments and well-wishers were able to fundraise and distributed vouchers
Businesses experience some level of growth with e-commerce and online payments .
ii) What is the meaning of electronic funds transfer?
(1mk)
EFT (electronic fund transfer) - us used to move money from one account to another. Or from case of
mobile phone transactions .The transactions are completed electronically, and the two accounts can be
at the same financial institution or different financial institutions. Term “EFT” is an umbrella term that
covers a broad range of electronic payments
8. Define the term dual booting as used in computing.
(1mk)
A dual boot is when you INSTALL two operating systems on one computer and being able
to choose which one to boot
(correct @1mk)
9. Differentiate between cropping and grouping.
(2mks)
Cropping is removing unwanted parts of a graphics
Grouping is combining more than one object to be manipulated as one
(correct @ 2mks)
10. Other than pseudocode, state two tools that can be used to present an algorithm
●
●
●
(2mks)
flow chart
Decision Tables
Decision Trees
(any two @2mks)
11. Differentiate between a deadlock and interrupt as used in operating system.
(2mks)
Deadlock refers to a situation whereby a particular job holds a resource and refuses to
release it yet it is requesting for a resource held by another job
Interrupt is a break from the normal sequecial processing of instructions in a program
(Correct @2mks )
12. (a) Securem is a company that deals with providing security services to its clients. Name any
two ways the company can protect its computer network from hackers.
(2mks)
●
●
●
●
Log files
Data encryption
Use of passwords
Firewalls (first 2 @2mks)
(b) State three characteristics of a suitable password.
-
Easy to remember
Hard to guess
Should be a combination of letters and numbers
5
(3mks)
-
Should be a minimum of 8 character (first 3@3mks)
-
13. During system development the system analyst should consider the correct requirement
specifications for the new system. State any four outcomes that may result from using incorrect
requirement specifications. (3mks)
●
●
●
●
●
More costs than was projected
The system will be delivered later than schedule
The system will not meet user’s expectations
The cost of maintaining and enhancing the system may be excessively high
The system may be unreliable and prone to errors and downtime
(first 4 @ 4mks)
14. (a) Define the term Computer Aided Design.
(1mk)
A system of programs and workstations used in designing engineering, architectural and
scientific models ranging from simple tools to building.
(correct @ 1mk)
14.(b) List two advantages of using Computer Aided Design.
●
●
●
●
(2mks)
The length of time taken to draw is reduced
Easier to make changes or update the original design
Duplicates of the design are easy to produce, distribute to various interested parties
It is easier to view the end product before it is designed
(first 2 @2mks)
15. Explain two arithmetic errors that may occur during computerised data processing.
●
●
●
(2mks)
Truncation error
Rounding off error
Overflow error
(state @½ mk , explain @½ mk, total 1mk each)
SECTION B: 50 MARKS
Answer Question 16 and any other three questions from this section in the spaces provided.
16. (a) Give two examples of syntax errors in programming.
●
●
●
Punctuation mistakes
Improper naming of variables
Wrong spellings of user defined and reserved words.
(2mks)
(first 2@2mks)
16.(b) Scrabble is a word game where the players are awarded points by creating words from a
combination of letters each of which carry a different point value. A player is awarded the points for
creating words from the combination. Write a pseudocode to read a letter and output the value
equivalent to that letter from the following table. (8mks)
6
LETTER
VALUE
A,E,I,L,N,O,R,S,T,U
1
D,G
2
B,C,M,P
3
F,H,V,W,Y
4
K
5
J,X
8
Z,Q
10
START……………………………………………..½ MK
READ letter…………………………………..1 MK
CASE letter of
………………………………1 MK
‘A’,’E’,’I’,’L’,’N’,’O’,’R’,’S’,’T’,’U’:marks=1;....... ½ MK
‘D’,’G’:marks=2;……………. …………..½ MK
‘B’,’C’,’M’,’P’:marks=3;………… …………..½ MK
‘F’,’H’,’V’,’W’,’Y’:marks=4;..................½ MK
‘K’:marks=5; ……………….½ MK
‘J’,’X’:marks=8; ………………….½ MK
‘Z’,’Q’:marks=10; ………………. ½ MK
ELSE
PRINT ”INVALID CHARACTER” ………… ½ MK
END CASE
PRINT marks ………..1MK
STOP…………….. ½ MK
START/STOP >1MK
INPUT > 1MK
CORRECT USE OF SELECTION(CASE) > 1MK
EACH CONDITION > ½ MK
OUTPUT > 1MK
(c) Classify the following programming languages according to their category:
7
(3mks)
Programming language
Category
HTML
Web scripting (½mk )
JAVA
OOP (½mk )
JAVASCRIPT
Web scripting (½mk )
PASCAL
3GL (½mk )
VISUAL BASIC
4GL (½mk )
LISP
5GL (½mk )
(d) With aid of a diagram, explain the “Repeat Until” construct as used in structured programming (2mks)
- the program first executes then tests the condition and
continues looping until the condition turn to true
-
The program tests and then executes until the condition becomes true
(diagram @1mk, correct explanation @ 1mk)
17. (a) State the stage in system development life cycle where each of the following activities are
carried out:
i. Identifying shortcomings of a system.
(1mk)
Problem definition (correct @1mk)
ii. Preparing the system migration plan (1mk)
Implementation stage (1mk)
iii. Identifying the technologies that may be used in the proposed system. (1mk)
system analysis(correct @1mk)
(b) State three roles of a programmer in system development life cycle. (3mks)
8
-
Coding/writing code for the new program
Turning system specification into an information system
Modify existing programs to meet changes in information processing needs
Installing a system
Testing the new system
Developing technical guide/documenting
(first three @ 3mks)
(c) E-mail technology has become a very important part of today’s communication. Explain any
three problems associated with using e-mail technology for communication.
(6mks)
●
●
●
●
●
●
Threat to privacy
Messages can be sent to many people without their consent
Email attachments can be sources of viruses
Not available to all/technology illiteracy
Emails can be unsolicited/spam mail
Encourage illicit communication such as immoral behaviour
(first 3 @2mks each)
(d) Sarafina wants to download her favourite movie from YouTube. State any three factors that
may determine how long it will take her to complete the download.
(3mks)
●
●
●
●
Other activities that may be running in the computer
Bandwidth of the media used
Size of the video
Other restrictions enforced in the computer
(first 3 @ 3mks)
18. The following Digital Club Member details were to be entered in a database: Name, Date of
registration, Registration fee and Class.
(a) Prepare a suitable structure showing field names and their field types
Field
Data type
Name
Text (✓1mk)
Date of registration
Date(✓1mk)
Registration fee
Currency or Number(✓1mk)
Class
Text(✓1mk)
(4mks)
(b) Name one other field that the Club Patron may need to add to uniquely identify the records
(1mk)
Member Number
(✓1mk)
(c) Write the statement that can be used to select members of the class form 3
9
(2mks)
Name
Date of
registration
Registration fee
Class
Form 3 (✓1mk)
Criteria/
Expression
(d) The following is an extract from a spreadsheet created to manage sales. Use it to answer
the questions that follow.
A
B
C
1
ITEM NAME
UNIT PRICE
UNITS SOLD
2
HDD 300 GB
7,500 2
3
Optical Drive
4,500 8
4
DELL Latitude core i5
44,500 3
5
DDR4 8GB RAM
10,000 4
6
Lenovo Yoga Smart Tab
28,953 1
D
(i) Write a formula that will compute the number of items whose unit price whose price more than
10,000
(3mks)
=COUNTIF(B2:B6,”>10,000”) OR @COUNTIF(B2:B6,”>10,000”) OR
+COUNTIF(B2:B6,”>10,000”)
❖ (B2:B6) Argument range @1 mark
❖ (>10,000) Criteria @ 1 mark
❖ All Formula correct @ 1 mark
(ii) If the formula =$B2*C$2 was placed in D2, state the output if copied to D3
(2mks)
❖ Formula is =$B3*C$2 @ 1 mark
❖ =4,500*2
❖ = 9,000 @ 1 mark
(iii) Write the cell referencing used in c(ii) above
(1mk)
Mixed cell referencing
(iv) Write the data type that is stored in cell C5 and A6 respectively
(2mks)
C5-Value
A6- label
10
19. a) Define the term attenuation as used in networking and data communication
(1mk)
It refers to the weakening of signal strength as it progressively moves from one point to
another on the transmission media.
(b) The following are figures of networking cables. Identify each.
(2 marks)
Figure 1
Figure 3
Figure 2
Figure 4
Figure 1: Unshielded Twisted Pair (UTP)
Figure 2: Shielded Twisted Pair (STP)
Figure 3: Coaxial
Figure 4: Fibre optic
(Each @ ½ mark)
c) (i) Give TWO examples of network software
(2mks)
❖ Network operating system
❖ Network protocols
(ii) In a network setup, list any TWO items that may be referred to as data terminal equipment.
(2mks)
❖ Computer
❖ Printer
❖ Visual Display Unit
11
d) Explain the following terms as used in networking
(4mks)
(i) Remote Communication
It involves transmission of data signals between two communication devices located at
different geographical location, through which people can be able to share ideas over
network
(ii) Distributed processing
This involves the subdivision of a process into several subprocess then each subprocess
can be processed at a different site co-currently hence speeding up the entire process
e) State FOUR functions of a server in a network
(4 marks)
It allows sharing a network printer
It allows communication between the various workstations in a network
It provides control access to available storage devices in network
It allows sharing of communication. Files in the network
It provides the transfer of files from one workstation to another workstation in the network.
20.
(a) Determine the binary equivalent of the octal number 253243.
(2 marks)
0100101011010100011
(b) Carry out the following binary arithmetic using ones complement. In each case leave your
answer in base 10.
(i) 1010-108
(5 marks)
Binary equivalents table
Binary Bits
Decimal equivalent
000
0
12
001
1
010
2
011
3
100
4
101
5
110
6
111
7
1000
8
1001
9
1010
A
1011
B
1010-1010
108 - 001000
Make the digits of the values the same
001010
-001000
Complement the negative value
110111
Add the complemented value to the positive value
001010
+
110111
(1)000001
Add the overflow digit to the LSD
000001
+
1
13
Ans
0000102
Convert it to decimal
210
(i)
2BH-9H
(6 marks)
2BH - 00101011
9H -1001
00101011
1001
Make the digits of the values the same
00101011
- 00001001
Complement the negative value
11110110
Add the complemented value to the positive value
+
00101011
11110110
(1)0010000
Add the overflow to the LSD
001000102
Convert the answer to decimal
3410
(c) Arrange the following numbers in ascending order.
1016,
1010,
158,
10112
1010, 10112, 158, 1016,
14
(2 marks)